#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int arr[5];
	int i, s = 0;
	double ave = 0;
	for (i = 0; i < 5; i++)
		scanf("%d", &arr[i]);
	for (i = 0; i < 5; i++)
		s += arr[i];

	ave = s / 5.0;
	printf("%.1lf", ave);
	return 0;
}
